(a) Field of the Invention
This invention relates to chewable calcium carbonate-containing antacid tablets.
(b) Description of the Prior Art
The use of calcium carbonate as the effective acid neutralizing agent in antacid tablets is known. The problem with calcium carbonate as an ingredient in antacid tablets, however, is that, unless formulated in special ways, it produces tablets which taste gritty and chalky and which thus lack the desirable quality in chewable antacid tablets known as good "mouthfeel". The problem of overcoming this undesirable gritty and chalky taste in chewable calcium carbonate-containing antacid tablets has either been ignored by the prior art, or the problem has been addressed by use of flavoring agents or other ingredients intended to mask the undesirable taste.
Thus neither Palermo, U.S. Pat. No. 3,384,546, which discloses, in Example 6, a chewable antacid tablet containing calcium carbonate, magnesium trisilicate, mannitol, sorbitol, sodium saccharin, mint flavoring and magnesium stearate, nor British Pat. No. 1,056,212 which discloses the use of a combination of urea and glycine as an extended buffering agent for calcium carbonate, addresses the question of the chalky taste of calcium carbonate containing antacids.
Diamond et al., U.S. Pat. No. 3,843,778, which discloses the use of calcium carbonate as one of several "preferred" ingredients for antacids, overcomes the taste problem by coating the calcium carbonate particles with oil. The particle size of the antacid ingredient is disclosed as being in the range from 0.5 to 300 microns, although no reason for the particular choice of particle size is given. In British Pat. No. 1,401,256 the chalky taste of calcium carbonate-containing antacids is overcome by spray drying the calcium carbonate with a surfactant which also aids in dissolution of the tablet.
Granatek, U.S. Pat. No. 3,452,138 teaches that mannitol provides a very astringent tablet which must be taken with water, while Rubino, U.S. Pat. No. 4,115,553 discloses the use of basic aluminum bicarbonate/carbonate co-dried with a di- or trihydroxyalcohol to provide chewable antacid tablets with a good disintegration rate. The use of mannitol alone or in combination with sorbitol is also described, and sucrose is disclosed as an excipient that can be used either instead of, or in combination with, mannitol.
A number of publications have reported studies comparing the relative antacid efficacies of calcium carbonate and other acid neutralizing agents. For example Rider et al., Clin, Med., 73, 44-46 (1966) describe comparative tests in patients suffering from various stomach ailments using antacid tablets made either from calcium cabonate, magnesium carbonate or a powdered milk/cream formula; Broda et al., Farm. Pol., 36(4), 215-219 (1980); C.A., 93, 173683g (1980) describe tests to determine the relative acid neutralizing capabilities of different antacids containing either magnesium oxide, aluminum hydroxide, magnesium carbonate, basic bismuth nitrate, magnesium hydroxide, calcium carbonate or sodium bicarbonate; Van de Loo, Munchen med. Wschr., 118, 271-274 (1976) report the results of the clinical treatment of ulcerous diseases with antacids containing either aluminum hydroxide, magnesium carbonate or calcium carbonate; and Smyth et al., J. Pharm. Sci., 65 (7), 1045-1047 (1976) disclose the results of a study of the correlation between in vitro and in vivo methods for assessing antacids containing either magnesium hydroxide, aluminum hydroxide or calcium carbonate.
Other publications have reported studies on various physical properties of calcium carbonate-containing antacids. For example Madee et al., Arzneimittel Forsch., 25 (1), 122-123 (1975) report a comparison of the disintegration rates, as measured by an intragastric pH probe, of two formulations of calcium carbonate-containing antacid tablets, one in which the particles were wax coated and the other in which they were uncoated; and Salakawy et al., Pharmazie, 27 (9), 595-599 (1972) report the results of a study of the cause of darkening of calcium carbonate/glycine-containing antacid tablets in the presence of aldo or keto sugars.